Competition for shifting resources in the southern Benguela upwelling: Seabirds versus purse-seine fisheries
Competition for shifting resources in the southern Benguela upwelling: Seabirds versus purse-seine fisheries
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DOI：
10.1016/j.biocon.2009.05.031
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发表时间：
2009-10-01
影响因子：
5.9
通讯作者：
Gremillet, David
中科院分区：
文献类型：
--
作者：
Okes, Nicola C.;Hockey, Philip A. R.;Gremillet, David
在南非西海岸外的南部本格拉上升流生态系统，由于中上层鱼类的供应减少，海鸟的数量正在急剧减少。我们测试的假设，西海岸的渔业是竞争的剩余库存的鲤鱼和沙丁鱼与最大的殖民地脆弱的海角塘鹅（桑capensis）沿着大西洋沿岸。使用GPS跟踪的鸟类，回声测深的中上层鱼类，船舶日志，我们位于鸟类觅食范围，中上层鱼类分布和渔业活动之间的重叠区域。然后，我们比较了塘鹅和船只在其联合觅食区的渔获量。2007年10月，围网渔场和塘鹅觅食区仅重叠13%。然而，在一个月的时间里，围网渔船从这一地区捕捞的鱼类数量相当于在马尔加斯岛繁殖的72，000只塘鹅（占世界人口的25%）食物需求的41%。该地区的渔业捕捞量对塘鹅的潜在影响很大，但仅占渔业总捕捞量的3.6%。根据这一发现、塘鹅群体的迅速缩小以及南非1998年《海洋生物资源法》的既定目标，考虑和试验围网渔业海上“禁捕”区的理由很充分。努力确定“禁捕”捕鱼区是否会增加顶级捕食者的食物供应，是保护南部本格拉生态系统的重要下一步。(C)2009爱思唯尔有限公司保留所有权利。
In the southern Benguela upwelling ecosystem off the west coast of South Africa, seabird populations are decreasing dramatically because of reduced availability of pelagic fish. We tested the hypothesis that the west coast fishing industry is competing for the remaining stocks of anchovy and sardine with the largest colony of Vulnerable Cape Gannets (Morus capensis) along the Atlantic coast. Using GPS-tracking of the birds, echo-sounding of pelagic fish, and vessel log books, we located overlap areas between bird foraging ranges, pelagic fish distribution, and fishing activities. We then compared fish catches by gannets and vessels within their joint foraging zones. In October 2007, purse-seine fishing grounds and gannet foraging areas overlapped by only 13%. However, for a 1-month period, the amount of fish removed from this area by purse-seine boats amounted to 41% of the food requirements of the 72,000 gannets breeding on Malgas Island (25% of the world population). The fishery's catch in this area is significant in terms of its potential impact on gannets, but comprises only 3.6% of total fishery catch. Based on this finding, the rapidly decreasing size of the gannet colony and the stated objectives of South Africa's Marine Living Resources Act of 1998, the case for considering and experimenting with at-sea 'no-take' areas for the purse-seine fishery is strong. Efforts to establish whether 'no-take' fishing zones increase food availability for top predators is an important next step in conservation of the southern Benguela Ecosystem. (C) 2009 Elsevier Ltd. All rights reserved.